1. Field of the Invention
This invention relates in general to enclosures for storage devices. Specifically, the present invention relates to enclosures with vibrational damping capabilities for receiving disk drive storage devices.
2. Description of the Related Art
In conventional disk drives, the data storage disk is mounted on a main body of the disk drive and is typically either mounted horizontally for rotation about a vertical axis or is mounted vertically for rotation about a horizontal axis. The disk head, which may be a read-only head or a read-and-write head is movably mounted on the main body of the disk drive in order to track across the disk to desired locations where data needs to be read or written. Such operations are known as “seek operations.” Although in some circumstances the disk drive may be permanently and rigidly fixed to the enclosure chassis, it often occurs that the disk drive must be mounted so as to be easily removable from the enclosure chassis. For example, file server products often house a number of hard disk drives in a single enclosure chassis, in order to meet storage requirements.
Whether the disk drives are mounted vertically or horizontally, a problem arises with regard to the operation of disk drives when mounted next to each other. The problem occurs during seek movements of the actuator across the disk. The rotational energy created by a disk drive actuator is often sufficient to move the body of the disk drive and create servo errors. Such movement can result in write inhibits, soft errors, and slow response time, generally characterized as self-induced problems. In recent years the actuators on disk drives have generally adopted a linear to rotary operation, in which the read/write head moves in an arc across the disk, rotating about a vertical axis (for a horizontal disk) on the main body of the disk drive outside the perimeter of the disk.
The acceleration and deceleration of such a rotary actuator produce rotary oscillation of the main body of the disk drive in a horizontal plane. The axis acceleration and deceleration of the actuator containing the read/write heads, particularly on high performance disk drives, results in an equivalent reaction to the main body of the disk drive. In addition, when the disk stack is out of balance, the rotating disks cause vibration in the drive. These vibrations may be transmitted through the enclosure chassis to adjacent drives sharing a common support, such as a mounting wall. This vibration transmission may result in write inhibits, soft errors, and slow response from the disk drives, generally characterized as vibration transmission problems.
Further, when the systems using the disk drives indicate problems generally attributable to damaged disk drives, the disk drive may be replaced, when in reality the disk drive is not damaged, rather vibration transmissions resulting from am enclosure chassis having insufficient stiffness and damping may be causing the problems.
As more tracks are written per inch on disk drives, the severity of the problems will increase as the read/write head makes increased movement across the disks. Thus, future disk drive products will require enclosure chassis that take vibration transmission more into account.
Current attempts to eliminate excessive vibration in disk drives have focused on damping springs mounted between disk storage device carriers and the enclosure chassis. In some situations, when the disk drive vibration transmissions are minor, the current methods may be adequate. However, in other situations when the disk drive vibration transmissions are greater, more protections are necessary. Additionally, the method of securing the springs to the disk storage device carriers is often time consuming and costly due to additional components and manufacturing processes.
Furthermore, current enclosure chassis are configured to accept any storage device carrier, regardless of the disk drive's interface (e.g., FC, SCSI, SATA, or SAS). Consequently, it is not uncommon for a disk drive or an enclosure chassis to be damaged when a disk drive with an incompatible interface is placed in an enclosure chassis. For example, when a disk drive having an FC interface is positioned into a enclosure chassis configured to receive a disk drive with an SCSI interface, either the disk drive interface is damaged, the enclosure chassis connection is damaged, or both are damaged.
Therefore, the design of the enclosure chassis and storage device carrier has a significant impact on the magnitude of the problems discussed above. The vibration transmission problems can be resolved with a very soft, or isolation type enclosure chassis construction. The self-induced problems can be solved with a very stiff or hard enclosure chassis construction. The solution to one problem, however, may counteract attempts to solve the other problem, or even aggravate the other problem. To resolve both problems, the enclosure chassis must have sufficient stiffness to minimize self-induced problems, and sufficient damping to prevent significant vibration transmissions from adjacent disk drives.
What is needed is an enclosure for a storage device that absorbs vibration transmitted from a disk drive to other disk drives mounted within the same enclosure minimizes self-induced vibration problems. There is also a need to decrease the manufacturing costs associated with the damping system, as well as to decrease error-related costs from damaged disk drive interface connections.